RockeTiltometer 3

RockeTiltometer

Dad to the RockeTiltometer series...
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Do not plan on providing the code...not sure from liability aspect that it makes sense to me, particularly if someone were to re-program the actual RTOM3...if you want, the core orientation engine code is Open Source at the MatrixPilot web site, though of course we revised it along the way for the specific feature sets of the RockeTiltometer series...hope that helps...
 

Chad

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Do not plan on providing the code...not sure from liability aspect that it makes sense to me, particularly if someone were to re-program the actual RTOM3...if you want, the core orientation engine code is Open Source at the MatrixPilot web site, though of course we revised it along the way for the specific feature sets of the RockeTiltometer series...hope that helps...
Very helpful! Thanks for the matrixpilot link
 

mtnmanak

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With the ROTM off the market, it looks to me like the only other real alternative in this price range is an Altus Metrum Easy Timer. The Easy Timer is not quite the same thing, but it can be used to serve the same function of controlling my airstarts with tilt limiting. I will miss the ROTM to add tilt limiting to my Protons, but I guess the alternative will be to move to Quantums for the parachute events and EasyTimers for the airstart events.

Is there anything else on the market like this? (Without moving to the eye wateringly expensive EasyMega or TeleMega)

If not, I think I will stock up on some EasyTimers before Altus Metrum raises the price/runs out of stock.
 

plugger

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With the ROTM off the market, it looks to me like the only other real alternative in this price range is an Altus Metrum Easy Timer. The Easy Timer is not quite the same thing, but it can be used to serve the same function of controlling my airstarts with tilt limiting. I will miss the ROTM to add tilt limiting to my Protons, but I guess the alternative will be to move to Quantums for the parachute events and EasyTimers for the airstart events.

Is there anything else on the market like this? (Without moving to the eye wateringly expensive EasyMega or TeleMega)

If not, I think I will stock up on some EasyTimers before Altus Metrum raises the price/runs out of stock.
just remember that the EasyTimer doesn't have any logging or data capabilities, at least for the v1 unit.
 

mtnmanak

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Eggtimer Quantum or Proton.

Having built and flown about 20 Protons and Quantums, I am pretty sure they do not have tilt monitoring for airstarts, unless Cris cleverly hid that gyro somewhere on the boards.
 

plugger

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Yeah, def not the same thing, but what else is there?
Honestly, either wait for the Blue Raven or bite the bullet and grab an EasyMega. Not being able to troubleshoot issues via data logging made me put my EasyTimer on the shelf.
 

mtnmanak

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The Blue Raven is going to have tilt built in so hopefully that fills the gap between the easytimer and easy/telemega

Excellent point, definitely looking forward to the Blue Ravens - they look like they will be an amazing computer
 

waltr

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Having built and flown about 20 Protons and Quantums, I am pretty sure they do not have tilt monitoring for airstarts, unless Cris cleverly hid that gyro somewhere on the boards.
Not directly.

The Proton can compare the Baro altitude to the Altitude derived from the Accelerometer. If the Baro Altitude is much less then the rocket is not going up enough therefore has tilted.
This is not a direct measurement of angle like integrated Gyro would be.

Years ago someone had a tilt device based on angle of Earth's magnet field with a single axis magnetic sensor. I have thought that using a 3D Magnetometer (Compass) chip and some math a tilt angle could be measured. Just have not figured out the math yet. I do have 3D Mag data from a number of flights.
 

Charles_McG

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The Diff(accel_alt - baro_alt) limit is a nice feature - but I've got a number of rockets where the surface shape throws a velocity dependent error into the baro data. So that Baro_alt is higher than accel_alt. Which is silly - flying straighter up than straight up? But that's what the data shows.

So I depend on the Actual_Alt > Planned Alt @ timer limit - and it's velocity equivalent. I've occasionally gotten the sim wrong - and hence the settings wrong, but so far it's always been in the conservative direction (don't light). Since I'm flying F-I size motors, I'm comfortable with the limits of these limits.

But I also understand the desire for better controls. Especially as the size goes up.
 

G_T

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Using the magnetic vector field is quite tricky in reality. It is affected by proximity to various metallic objects, such as perhaps the launch rail. And then the local ground conditions can have affect. It can change with elevation pretty quickly depending on what is under the ground where you are. It certainly changes greatly depending on where on the surface of the earth you start.

Tilt with respect to the magnetic pointing vector in reality traces a cone around that vector. That cone is only rarely somewhat coincident with the cone around vertical that you'd like to have. The magnetic poles, and a few other regions of the earth, are where it would work reasonably.

Gerald
 

waltr

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Yes, mag vector is tricky which is a reason I have not yet got any math to work.
But throwing out the idea for discussion.
 

jderimig

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Yes, mag vector is tricky which is a reason I have not yet got any math to work.
But throwing out the idea for discussion.
That is because you can't. You can determine the tilt from the magnetic field vector but not from vertical.
 

G_T

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As I tried to explain, that is mathematically impossible. An angle off a non-vertical vector traces a tilted cone.

It's also somewhat practically impossible, because the pointing vector will change when you leave the steel launch rail behind. So even what you think is the magnetic pointing vector is not a representation of the field you'll see even a few feet above the rail. Try it with a compass sometime.

You need at least one gyro - in the roll direction - to deal with the first problem. And it had better not drift. Even with that you'd still have the second problem which is not insignificant. Besides, once you've got gyros, use them.

Magnetic vector is interesting, but mostly useless. You might be able to use it for determining spin rate.

Gerald
 

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